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97 lines
2.5 KiB
Python
97 lines
2.5 KiB
Python
# Sebastian Raschka 2014
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# Prints Information of a SQLite database.
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# E.g.,
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#
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"""
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Total rows: 1
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Column Info:
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ID, Name, Type, NotNull, DefaultVal, PrimaryKey
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(0, 'id', 'TEXT', 0, None, 1)
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(1, 'date', '', 0, None, 0)
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(2, 'time', '', 0, None, 0)
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(3, 'date_time', '', 0, None, 0)
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Number of entries per column:
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date: 1
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date_time: 1
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id: 1
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time: 1
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"""
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import sqlite3
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def connect(sqlite_file):
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""" Make connection to an SQLite database file """
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conn = sqlite3.connect(sqlite_file)
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c = conn.cursor()
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return conn, c
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def close(conn):
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""" Commit changes and close connection to the database """
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# conn.commit()
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conn.close()
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def total_rows(cursor, table_name, print_out=False):
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""" Returns the total number of rows in the database """
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cursor.execute('SELECT COUNT(*) FROM {}'.format(table_name))
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count = cursor.fetchall()
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if print_out:
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print('\nTotal rows: {}'.format(count[0][0]))
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return count[0][0]
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def table_col_info(cursor, table_name, print_out=False):
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""" Returns a list of tuples with column informations:
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(id, name, type, notnull, default_value, primary_key)
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"""
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cursor.execute('PRAGMA TABLE_INFO({})'.format(table_name))
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info = cursor.fetchall()
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if print_out:
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print("\nColumn Info:\nID, Name, Type, NotNull, DefaultVal, PrimaryKey")
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for col in info:
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print(col)
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return info
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def values_in_col(cursor, table_name, print_out=True):
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""" Returns a dictionary with columns as keys
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and the number of not-null entries as associated values.
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"""
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cursor.execute('PRAGMA TABLE_INFO({})'.format(table_name))
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info = cursor.fetchall()
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col_dict = dict()
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for col in info:
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col_dict[col[1]] = 0
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for col in col_dict:
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c.execute('SELECT ({0}) FROM {1} '
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'WHERE {0} IS NOT NULL'.format(col, table_name))
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# In my case this approach resulted in a
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# better performance than using COUNT
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number_rows = len(c.fetchall())
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col_dict[col] = number_rows
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if print_out:
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print("\nNumber of entries per column:")
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for i in col_dict.items():
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print('{}: {}'.format(i[0], i[1]))
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return col_dict
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if __name__ == '__main__':
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sqlite_file = 'my_first_db.sqlite'
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table_name = 'my_table_3'
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conn, c = connect(sqlite_file)
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total_rows(c, table_name, print_out=True)
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table_col_info(c, table_name, print_out=True)
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# next line might be slow on large databases
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values_in_col(c, table_name, print_out=True)
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close(conn)
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